At least 37 people killed and over 350,000 affected after mudslides cover villages in worst-hit Kegalle district.

Hopes of survivors were fading as rescue efforts have been hampered after heavy rains continued to pound the central Sri Lankan region where villages have been swallowed by mud in several landslides.

Military spokesman Brigadier Jayanath Jayaweera told reporters in the capital, Colombo, on Thursday, that the army was assessing the situation and would deploy more troops in the worst-hit Kegalle district if needed.

"I don't think there will be any survivors," Major General Sudantha Ranasinghe, the officer in charge of the rescue operation, told Reuters.

"There are places where the mud level is up to 30 feet. We will do our best. We will keep going until we can recover the maximum."

At least 37 people have been killed and nearly 220,000 displaced by landslides which crashed into at least three villages in Aranayaka, in the central hills of Sri Lanka, following torrential rains.

Jayaweera said that the army had so far rescued 156 people trapped by landslides and more than 1,550 people were being sheltered at seven different sites.

The Disaster Management Centre reported more than 350,000 people were affected by the landslides. About 220 families were reported missing, the Sri Lankan Red Cross said in a statement on Wednesday.

"The task is to figure out what happened to them," the Red Cross said, noting that some people may have left after local officials warned earlier this week of possible landslides.

A government official who is part of the rescue efforts said on Wednesday from Kegalle district, about 72km from Colombo, that one village, Siripura, was buried 12 metres under the mud.

Villagers recalled hearing and seeing the torrents of muddy water, tree branches, and debris crashing down around their homes late on Tuesday.

"I heard a huge sound like a plane crashing into the earth," AG Kamala, 52, who had just returned to her house in Siripura when the landslides hit the area, told the Associated Press news agency.

"I opened my door: I could not believe my eyes as I saw something like a huge fireball rolling down the mountain - and again a huge sound."

Officials could not provide exact figures on the village populations, but each typically includes about 1,000-1,500 residents.

Rikaz Hussain, the government official, said: "It's absolutely mind-boggling what sort of disaster this has turned out to be.

"It seems like someone cut off a mountain and planted it on top of the village. There are absolutely no signs of a village ever existing here. There's no sign of Siripura. The rescue efforts here are futile."

Hampered by rain

Hussain said sporadic rain was hampering the work of the rescue squad as rain continued to fall, increasing the changes of more landslides in the area.

"There are so many other sites and villages affected," he said.

"Some of the roads are also inundated, so we can't even get through to those affected. Some places are not even accessible by helicopter."

One woman, AG Alice, said all nine of her children were unaccounted for.

"I don't know what happened to me after" the landslides hit with "a thundering sound I have never heard in my life," she said.

More than 1,000 people who escaped the disaster were provided shelter and medical treatment for minor injuries at a nearby school and a Buddhist temple, according to Mahendra Jagath, a government official.

Officials gave warning that more landslides and lightning strikes could occur in the countryside, as more rain was forecast in addition to rough seas along the coasts.

Mudslides are common in Sri Lanka during the monsoon season, with heavy deforestation to clear land for agriculture leaving the countryside exposed.